Image recording apparatus having sheet nip releasing mechanism and shutter mechanism

Abstract

An image recording apparatus having reversal feed means for feeding an elongated photosensitive sheet in a reverse direction. The photosensitive sheet undergoes exposure operation and a pressure developing operation. Since unexposed zone is positioned subsequent to the exposure zone, the unexposed zone is also positioned at downstream side of the exposure portion by the pressure developing operation to the preceeding exposure zone. The reversal feed means is adapted for moving an unexposed zone of the photosensitive sheet positioned at downstream side of the exposure portion to an upstream side thereof. A sheet nip releasing mechanism is provided in the apparatus for releasing sheet nipping force given by feed rollers during the reversal sheet feeding. Further, a shutter mechanism is provided for avoiding light irradiation to the unexposed zone during the reverse travel.

What is claimed is: 
     
       1. An image recording apparatus for forming a latent image on a rolled photosensitive sheet, the latent image corresponding to an image of an original, and for forming a visible image on a developer sheet, the visible image corresponding to the latent image, the apparatus comprising; a cartridge shaft on which the rolled photosensitive sheet is provided;   an exposure portion on which the photosensitive sheet is positioned to form the latent image thereon, to thus provide an exposed zone, an unexposed zone being subsequent to the exposed zone;   a pressure developing unit positioned downstream of the exposure portion for superposing the exposed zone with the developer sheet and for pressing these sheet together for forming the visible image on the developer sheet;   a separation means positioned downstream of the pressure developing unit for separating the photosensitive sheet from the developer sheet;   a takeup means positioned downstream of the separation means for taking up the light exposed photosensitive sheet thereover, the photosensitive sheet being fed in one direction from the cartridge shaft to the takeup means;   feeding means positioned between the exposure portion and the pressure developing unit for nippingly feeding the photosensitive sheet toward the pressure developing unit at a constant speed in the one direction;   a sheet nip releasing mechanism connected to the feeding means for releasing the sheet nipping force of the feeding means when the unexposed zone of the photosensitive sheet is moved from the downstream portion of the exposure portion to the upstream portion thereof after the photosensitive sheet is separated from the developer sheet; and   a reversal feed driving means for moving the photosensitive sheet in a second direction opposite the one direction.   
     
     
       2. The image recording apparatus as claimed in claim 1, wherein the reversal feed driving means comprises the cartridge shaft which is rotatable in the second direction for winding the photosensitive sheet thereover. 
     
     
       3. The image recording apparatus as claimed in claim 2, further comprising: a dancer roller positioned between the feeding means and the pressure developing unit and movable between a sheet slack absorbing position and a non operative position; and   drive means for driving the dancer roller between the sheet slack absorbing position and the non operative position, the drive means driving the dancer roller to the sheet slack absorbing position during the exposure operation, and driving the dancer roller to the non operative position during the travel of the photosensitive sheet in the second direction.   
     
     
       4. The image recording apparatus as claimed in claim 2, wherein the feeding means comprises a drive roller and a pinch roller having a pinch roller shaft movable toward and away from the drive roller, the photosensitive sheet being nipped between the drive roller and the pinch roller for feeding the photosensitive sheet in the one direction. 
     
     
       5. The image recording apparatus as claimed in claim 4, wherein the sheet nip releasing mechanism comprises; a first link having one end rotatably supporting the pinch roller shaft and having another end;   a biasing means connected to the pinch roller shaft for normally urging the pinch roller toward the drive roller;   a pivotable second link having one end pivotally connected to the another end of the first link, and having another end;   a wire member having one end connected to the another end of the second link, and having another end;   a pivotable lever having one end connected to the another end of the wire member and having another end; and   a rotatable cam member in contact with the another end of the pivotable lever for pivotally moving the lever, whereby the pinch roller 12 is selectively moved away from the drive roller 11 for releasing sheet nipping between the pinch roller and the drive roller.   
     
     
       6. The image recording apparatus as claimed in claim 2, further comprising; means for detecting a length of reversal feed amount of the photosensitive sheet, the detection means comprising an encoder provided in a roller positioned upstream of the exposure portion.   
     
     
       7. The image recording apparatus as claimed in claim 2, wherein an optical path is defined reaching the exposure portion, and the image recording apparatus further comprises a shutter mechanism comprising a shutter provided movable to a retract position for allowing a light to direct to the exposure portion and a closing position for blocking the light on the optical path, and means for driving the shutter to the retract position during the exposure operation and to the closing position during the reversal feed of the photosensitive sheet, whereby the light irradiation to the unexposed zone is avoidable during the reversal feed. 
     
     
       8. An image recording apparatus for forming a latent image on a rolled photosensitive sheet, the latent image corresponding to an image of an original, and for forming a visible image on a developer sheet, the visible image corresponding to the latent image, the apparatus comprising; a cartridge shaft on which the rolled photosensitive sheet is provided;   an exposure portion on which the photosensitive sheet is positioned to form the latent image thereon, to thus provide an exposed zone, an unexposed zone being subsequent to the exposed zone, an optical path being directed to the exposure portion;   a pressure developing unit positioned downstream of the exposure portion for superposing the exposed zone with the developer sheet and for pressing these sheet together for forming the visible image on the developer sheet;   a separation means positioned downstream of the pressure developing unit for separating the photosensitive sheet from the developer sheet;   a takeup means positioned downstream of the separation means for taking up the light exposed photosensitive sheet thereover, the photosensitive sheet being fed in one direction from the cartridge shaft to the takeup means;   a reversal feed driving means for moving the photosensitive sheet in a second direction opposite the one direction in order to move the unexposed zone positioned downstream of the exposure portion to the upstream side thereof, and   a shutter mechanism having a shutter movable between a retract position for allowing a light to direct to the exposure portion and a closing position for blocking the light on the optical path, and means for driving the shutter to the retract position during the exposure operation and to the closing position during the reversal feed of the photosensitive sheet, whereby the light irradiation to the unexposed zone is avoidable during the reversal feed.